In general, a cooling apparatus is an apparatus employing a refrigerant compression type refrigerating cycle provided with a compressor, a condenser, an expansion apparatus and an evaporator and using cold air generated by a phase change of the refrigerant. The cooling apparatuses employing the refrigerant compression type refrigerating cycle includes representatively well-known air conditioners, refrigerators and the like.
A constant-speed type compressor driven at constant speed and an inverter type compressor capable of controlling rotation speed have been introduced as refrigerant compressors (hereinafter, referred to as compressor) employed in the refrigerant compression type refrigerating cycle.
A compressor, in which a driving motor (typically, an electric motor) and a compression part operated by the driving motor are all installed in an inner space of a hermetic casing, is referred to as a hermetic type compressor, and a compressor of which the driving motor is separately installed outside the casing is referred to as an open type compressor. Home or commercial cooling apparatuses usually employ the hermetic type compressor. Such hermetic type compressors may be categorized into a reciprocating type, a scroll type, a rotary type and the like according to a refrigerant compression mechanism.
The rotary compressor compresses a refrigerant by use of a rolling piston eccentrically rotating in a compression space of a cylinder and a vane contacted with a rolling piston for partitioning the compression space of the cylinder into a suction chamber and a discharge chamber. In recent time, a variable capacity type rotary compressor capable of varying a cooling capacity of the compressor according to the change in a load has been introduced. Well-known technologies for varying the cooling capacity of the compressor include applying an inverter motor, and varying a volume of a compression chamber by bypassing part of a compressed refrigerant out of a cylinder. However, for employing the inverter motor, a driver for driving the inerter motor is about 10 times as expensive as a driver of a constant-speed motor, thereby rising a fabrication cost of the compressor. On the other hand, for bypassing the refrigerant, a piping system becomes complicated and accordingly a flow resistance of the refrigerant is increased, thereby lowering efficiency of the compressor.
Considering such drawbacks, a so-called independent suction type variable capacity rotary compressor (hereinafter, referred to as independent suction type rotary compressor), in which a plurality of cylinders are provided and at least one of them is allowed for idling, is introduced. The independent suction type rotary compressor is configured such that each of the plural cylinders has a rolling piston and a vane for forming a compression chamber together with the rolling piston, and at least one vane is supported by a variable pressure applied thereto. A mode switching device for varying pressure is connected to a rear side of the vane.